Modified acrolein-pentaerythritol resins



United States Patent O" 2,909,506 Monrumn'acnoLum rnurAnnrrrmlroL RESINS a Howard B. Guest, Charleston, Joe T, Adams, St. Albans,

and Ben W. Kiir, Qua, W; Va assignors to Union Carbide Corporation, a, corporation ofNew York No Drawing. Application July 10,1956

Serial No. 596,8'14

m m; cram-67) The subject of this invention is a resin formed. by the condensation ofacrolein and pentaerythritol and a modi- CHFCH-C o OHCH=CH:

' oon, 03,0

tionality, Thus, pentaerythritol has a functionality of four as'a polyhydric alcohol and, acrolein has a functionality of three, cons'ideringjthe reactivity of both the carbonyl. group and the olefiriic group.- The pre-lcondensate thus formed on r'ea'cting' about three moles-ofpentaerythritol and. about four moles of acrolein in the presence of an acid catalyst is a"viscous liquid or'A-stage resin which slowly condenses to a solid plastic. However, for practical applications, the condensation can be stopped by the neutralization ofthe' catalyst. The neutral ;v 3

liquid pre-conden'sate can be stored until neededfand can then be hardened into a plastic by the additionjo'f a mineral acid or a strong organic acid. However; this method has the disadvantage that the resulting, plastic materials'hayeveiypoor impact strength. i

Patented Oct. 20, 1959,

'. the A-stage resin, it is possible to adjust the properties of the cured polymer. Thus, if the reaction is stopped when the viscosity of the mixture is 50 to.75 cps, and the resin, after removal of volatile materials, is cured with another catalyst, the polymer so' produced has a relatively high heat distortion point of about 90 0. to 100 C. or higher but only moderate impact strength- On the other hand, if the reaction is continued until the viscosity of .the' reaction mixtureis 75 to 350 cps;,'=the polymer made from such material has a lower heat .dis-' 'tortion point, but excellent impact strength. Efforts to obtain resins of optimum properties byiblending high and low viscosity resins have not been too promising.

' While the viscosity of the reaction mixture can be used as a control measure to determine the resin viscosity desired, a more precise determination of the viscosity of the A-stage resin is accomplished after stripping oil volatile material. Thus, after removing volatile materials, for instance, those which boil below 150 C. at atmospheric pressure, a low viscosity A-stage resin may be defined as one having a viscosity of 5000 to 25,000 cp's. at 40 C. Similarly, a high viscosity resin may be con sidered to have a viscosity of 25,000 to 500,000 cps; at 40C.

It has now been found that resins having excellent'heat distortion points and good impact strength can be obtained by adding a small. amount, i.e. from 2 to 7.5%, of 3,9-diviny1spirobi(in-dioxane), to the liquid A-s'tage resins, and curing the resins in the presence of an acidic catalyst. If larger amounts of the divinyl compound within the range of 7.5 to 25% of the total composition and pentaerythritol in reciprocal proportion to their func- As de'scrib'ediri our copen'd'iiig application Serial No.

596,431,filed July9, 19 56, "entitled Catalytic Process for Making Stable Acrolein-Pentaerythritol' Condensates, it has .been found that. hydrochloric acidis an excellent catalyst for' the first stage or aeetal reaction between acrolein and -pentaerythritol.'- However, this acid is a poor catalyst for the curing oretherification reaction, so

that completeremoval of the catalyst fromthe first or A-stage resin is not requiredinorder 'to obtain an A- stage viscositieswitliout danger'of, premature gelation eras reactants in the kettle. By control bf the viscosity of are added, cured polymers of still higher heat distortion points can be obtained, but at some sacrifice of impact strength.

Since 3,9-divinylspirobi(m-dioxane) melts at about 43 C., it 'is convenient to add it to the A-stage resin at a temperature of 45 C. or higher. The curing catalyst can then be added, conveniently dissolved in the spirobi compound, and the resin poured into the desired form and cured. I

High and low viscosity resins as previously defined difler from each other in two essential respects. Both the high and low viscosity resins can be considered as consisting of a 3,9-divinylspirobi(m-dioxane) or a reactive solvent moiety and a polyether-acetal resin moiety. The

viscosity of a composition is a function not only of the amount of 3,9-divinylspirobi(m-dioxane) present, but also the degree of condensation that has entered into the formation of the polyether-acetal resin moiety. Thus the addition of the 3,9-divinylspirobi(hi-dioxane) to a high viscosity resin to equal the known 3,9-divinylspirobi(mdioxane) content of a normally low viscosity resin will not produce identical compositions. The higher molecular weight of the polyether acetal moiety originally residing in the high viscosity resin remains a distinguishing characteristic even after dilution with 3,9-divinylspirobi(m-doxane). Hence finished resins cured from intermediate compositions with equal amounts of 3,9-divinylspirobi'(m-dioxane) will difier' in their physical properties depending upon the nature of the polyether-acetal structure present in the intermediate stage. Since high impact strengths rather than high heat distortion values are associated with a high molecular weightyof this intermediate polyether-acetal structure, the addition of 3,9-di vinylspirobi(m-dioxane) in appropriate quantities to high viscosity resins as previously defined makes possible high impactresins in the cured stage with vastly improved heat distortionvalues. if Q The use of the 3,9-divinylspirobi(rm-dioxane) is "not confined to those resins in, which "theA-stage material is prepared using hydrochloric acid as catalyst. If so desired, the first reaction between acrolein and pentaerythritol can be catalyzed by any one of several catalysts such as sulfuric acid, toluenesulfonic acid, or benzenesulfonic acid. While the mixture is still liquid the unsaturated acetal may be added in the desired amount and the resin then cured using the same catalyst which was present during the first reaction. In addition, if so desired, catalysts of this type may be used for the reaction to produce the A-stage polymer and when it is completed the acid may be neutralized with a base, such as sodium carbonate or sodium acetate. The 3,9-divinylspirobi(m-dioxane) may then be added and the resin cured in the desired fashion.

If the unsaturated acetal is added to A-stage material which has been produced using hydrochloric acid in the process described above, any one of a number of acids or acid-reacting compounds can be used as curing catalysts. Among these are sulfuric acid, toluenesulfonic acid, benzenesulfonic acid, phosphoric acid, stannic chloride, aluminum chloride, boron trifluoride, ferric chloric, titanium tetrachloride, .and mixed alkanesulfonic acids (a mixture which is predominantly ethanesulfonic acid but which contains some methanesulfonic acid and propanesulfonic acid).

The reaction to produce the A-stage material is best accomplished at 70 to 80 C. althoughit can be run as low as 60 C. and range as high as 100 C. The reaction time may be varied from 30 minutes to five hours depending upon the viscosity desired. The molar ratio of acrolein to pentaerythritol may be varied from 1.3/1 to 1.9/1 and also affects the resin viscosity.

The resins may be cured at temperatures from 50 C. to 200 C. with the preferred range being 70 to 120 C. The curing time required may range from a few minutes to 72 hours depending upon the temperature. 50 C., as long as 72 hours may be required while at 150 C. as little as ten minutes may be sufficient. At 70 C. the usual curing time is 16 hours while at 100 C. from three to eight hours is required.

The cured resins of this invention may be used in any of the applications where rigid plastic materials of good strength and toughness, and light in color, are desired. Also, because of their excellent light stability and resistance to hydrolysis, they are valuable for'many fields now served by the methyl methacrylate resins, such as display signs, ornaments, fixtures, and dentures. The liquid resins may be used for sealing and potting compounds in the electrical industry. They are also valuable as laminating resins in making laminates of glass cloth.

4 7 EXAMPLE 2Q-EFFECT OF ADDED 3,9-DIVINYL- SPIROBI(M-DIOXANE) ON RESIN PREPARED WITH HYDROCHLORIC ACID CATALYST A charge of 232 grams of acrolein (94.1% 329 grams pentaerythritol and 1.79 grams of 37% hydrochloric acid was placed in the apparatus described in Example 1. The reaction was conducted at 7476 C. for 2 /2 hours. At the end of that time the viscosity of the mixture at C. was 138 centipoises. The volatile material was then stripped 01f to a kettle temperature of 76 C./4 mm. The stripped resin weighed 422-grams.

To 80 grams of this resin there was then added 0.3%

. toluenesulfonic acid dissolved in 25 cc. methyl acetate.

" Heat distortion C 58 Flexural modulus p.s.i... 354,000 Hardness, durometer D 81 Impact (Izod), ft.-lbs. per in. of notch 1.6

' at 100 C. for 8 hours.

Thus, at

EXAMPLE l.EFFECT OF ADDED 3,9-DIVINYL- 5 A charge of 232 grams of acrolein (94.1%), 320 grams pentaerythritol and 1.105 grams of sulfuric acid in 2 cc. of water was placed in a l liter reaction flask. The reactor was equipped with stirrer, thermometer, condenser, and nitrogen feed line. While the mixture was stirred and held under nitrogen atmosphere the temperature was raised to 75 C. and held at that point for 1% hours. The final viscosity of the reaction mixture was 128 cps. at 25 C. Portions of the resulting resin were stripped of volatile matter at 76-80 C./34 mm., and diiferent amounts of 3,9-divinylspirobi(m-dioxane) were added. The resins were then cured for 8 hours at 100C. The results were as follows:

To dilferent portions (65 to 78 grams) of the stripped A-stage polymer were added 0.24 gram toluenesulfonic acid dissolved in different amounts of 3,9-divinylspirobi (m-dioxane) to yield in each instance 80 grams of compound. The material was poured into molds and cured The cured resins had these properties:

. Impact 3,9-Divrnylsprrobr Heat Drs- Flexural Hardness, (Izod), (m-dioxane) Added, tortron, Modulus, Durometcr ft.-1bs.

Percent C. p.s.i "D" per in.

' of Notch EXAMPLE 3.--EFFECT OF ADDED 3,9-DIVINYL- SPIROBI(M-DIOXANE) ON RESIN PREPARED WITH HYDROCHLORIC ACID CATALYST To the apparatus described in Example'l, there was charged a mixture of 99 grams of acrolein (94.1%), 136 grams of pentaerythritol and 1.02 grams of 37% hydrochloric acid. After reacting for 30 minutes at 8082 C. the mixture had a viscosity of 128 cps. at 25 C. The resin was then stripped to a kettle temperature of 75 C. at 4 mm. To an 80 gram portion of the stripped A-stage material there was added 0.24 gram toluenesulfonic acid dissolved in 25 cc. of methyl acetate. After the solvent was stripped oil? the resin was cured in the usual way at 70 C. for 2 hours followed by 8 hours at 100 C. and it had these properties:

Heat distortion C..- 83 Flexural modulus p.s.i 395,000 Hardness, durometer D 84 Impact (Izod) (ft-lbs. per in. of notch) 1.6

Heat distortion C 102 Flexural modulus ..p.s.i 321,000 Hardness, durometer D Impac z d) (fit- 1 sper in. of notch) -7 Achargeof- 845 grams of acrolein. (96%), 1188 grams pentaerythritol, and 8.79 grams of 37% hydrochloric acid was charged to the apparatus described in Example 1. After reaction at 73-76 C. for 45 minutes the viscosity of the mixture was 160 cps. at 25 C. The volatile material was-then distilled off to a kettle temperature of 75 -C.-/7 The stripped resin weighed 1612 grams.

A 90-gram portion of this A-stage resin was mixed with 0.27 gram of mixed alkanesulfonic acid. After curing in the usual way for 8 hours at 100 C. the materialhad these properties:

Heat distortion C..- 76 Flexural modulus p.s.i 461,000 Hardness, durometer D 84 Impact (Izod) (ft-lbs. per in. of notch) 2.2

To" another90 grams portion of the stripped A-stage composition there was added grams of 3,9'-divinylspirobi(m-dioxane) and 0.3 gram mixed alkanesulfonic acid. After curing-at 100 C. for 8 hours in the usual way the resin hadthese properties:

Heat distortion C 91 Flexural modulus p.s.i 321,000 Hardness, durometer D 84 Impact (Izod) (ft-lbs. per in. of notch) 1.1

EXAMPLE 5.-EFFECT OF ADDED 3,9-DIVINYL- SPIROBI(M-DIOXANE) ON RESIN PREPARED WITH HYDROCHLORIC ACID CATALYST A large batch of A-stage resin was prepared in the following manner: The reactor was a 2'5-gallon glasslined vessel equipped with a condenser, agitator and steam vacuum jet. A charge of 56.5 pounds of acrolein (96.4%), 69.4 pounds of pentaerythritol and 186 grams of 37% hydrochloric acid was placed in the reactor and heated to 70 C. The mixture was held between 70 and 75 C. for 32 minutes. At the end of the reaction period the unreacted acrolein and water were stripped off to a kettle temperature of 73 C. at 3 mm.

To demonstrate the eifect of added 3,9-divinylspirobi- (m-dioxane) on the properties of the cured resin, a series of runs was made in which incremental amounts of the unsaturated acetal was mixed with the A-stage polymer before it was cured. In all of these experiments 0.3% of mixed alkanesulfonic acids was added as curing agent and the resins were cured for eight hours at 100 C. The results are summarized in Table I.

EXAMPLE 6 .3 ,9-DIVINYLSPIROBI( M-DIOXAN E) ADDED TO LOW-VISCOSITY RESIN To a two-liter reaction flask equipped with stirrer, thermometer, condenser and nitrogen feed line, there were charged 798 grams of 96.6% acrolein (13.75 moles), 1127 grams pentaerythritol (9.29 moles), and

6.24 grams of 37%- hydrochloric aha/The mixture was heated to 72 C. and held at 72-74 C. rfor 25 fill flutes. At "the end of that time the material had a viscosity of 63 cps. at 25 C.

The volatile material 'was then distilled oif to a kettle temperature of 71 C./7.5 mm. The residual A-s'tage resin had the following properties:

Viscosity at 40 C. cps 11,520 Equivalent weight by hydroxyl analysis '2 167 Observed molecular weight (uncorrected for low- I molecular weight components) 362 Equivalent weight by unsatu'ration analysis 234 Unreacted pentaerythritol percent.. 3

A portion only of the A-stage liquid was charged-to a still with a short unpacked column and stripped to a kettle temperature of 225/ 3 mm. Thea'mountfof 3,9- divinylspirobi(m-dioxane) distilled oif amounted to 24% of the charge. The resin remaining from this distillation had a molecular weight of 947. V q

The eifec't of adding additional 3,9-divinylspiroh'ij(mdioxane) to the other portions of the A-stage' resinwas determined in a series of experiments. All of these were cured at 100 C. for 8 hours with 0.3% mixed alkanesulfonic acids catalyst. The cured polymers had the following properties:

. Properties of CuredResin Percent Divinyl- Sample spirobl Heat Impact Hard- (m-diox Distor Strength ness, Flexural ane) tion, (Izod), -1t;- Duro- Modulus Added 0. lbs/in. of meter None 93 0. 8 369, 000 4. 6 99 0. 7 85 325, 000 10 105 0.8 85 325, 000 14. 6 105 0. 3 85 294, 000 20 0. 3 85 369, 000 24.6 88 0.6 85 246, 000

EXAMPLE 7.3,9-DIVINYLSPIROBI(M-DIOXANE) ADDED TO HIGH-VISCOSITY RESIN To the same reactor used in the preceding example, there was charged 798 grams of 96.6% acrolein (13.75 moles), 1127 grams of pentaerythritol, and 6.24 grams of 37% hydrochloric acid. The mixture was heated to 74 C. and held at 7476 C. for 55 minutes. At the end of that time the viscosity of the solution was 312 cps. at 25 C. The volatile material was then distilled off to a kettle temperature of 79 C./7 mm. The residual A-stage resin had the following properties:

Viscosity at 40 C. cps 192,000 Equivalent weight by hydroxyl analysis 192 Observed molecular weight (uncorrected for low-molecular weight components) 498 Equivalent weight by unsaturation analysis 314 Unreacted 3,9-divinylspirobi(m-dioxane) (obtained by stripping to 225 C./3 mm.)

percent 6.5

Unreacted pentaerythritol do 1 A series of experiments was made in which additional amounts of 3,9-divinylspirobi(m-dioxane) was added to the A-stage resin. These were then cured for 8 hours at 100 C. with 0.3% mixed alkanesulfonic acids catalyst. It will be seen that the total amount of the divinylspirobi- (m-dioxane) present in sample B was equivalent to that present in the unreacted state in the unmodified low-viscosity A-stage 1n the preceding example. The cured polymers had these propert1es:

Properties of Cured Resin Percent Divinyl- Sample spirobi Heat Impact Hard- (m-diox- Distor- Strength ness, Flexural ane) tion, (Izod), Duro- Modulus Added 0. ft.-1bs./in. meter of notch D None 83 1. 19 85 333, 000 17. 65 101 0. 5 85 346, 000 4. 6 91 1. 0 85 10 97 0. 55 85 364, 000 14. 6 100 0. 3 85 346, 000 96 0. 3 85 329, 000 24. 6 93 0.3 85 364, 000

It will be noted that, sample B had a heat distortion point of 101 C. as compared to 93 C. for sample A in the preceding example.

What is claimed is:

1. Process of making a curable composition which comprises reacting acrolein and pentaerythritol in the presence of an acid catalyst wherein from 1.3 to 1.9 moles of acrolein'a're reacted per mole of pentaerythritol to form a liquid condensate, stripping ofl? volatiles which are distillable from said condensate at temperatures of 71 C. to 80 C. and 3 mm. to 7.5 mm. of pressure to form a liquid resin, and adding monomeric isolated 3,9-divinylspirobi(m-dioxa.ne) to the liquid resin in an amount of 2% to of the total composition to form a curable composition.

2. Process of making a curable composition which comprises heating acrolein and pentaerythritol in the presence of an acid catalyst wherein from 1.3 to 1.9 moles of acrolein are reacted per mole of pentaerythritol to 3 form a liquid condensate, ceasing the heating step when the viscosity of the condensate when stripped of volatiles which are distillable from said condensate at-temperatures of 71 C. to 80 C. and 3 mm. to 7.5 mm. of pressure is from 25,000 to 500,000 cps. at 40 C, distilling said condensate to strip said volatile materials and to form a liquid resin, and adding monomeric isolated 3,9-divinyl- -spirobi(m-dioxane) to the liquid resin in an amount of 2% to 25 of the total composition to form a curable composition.

3. Process of making synthetic resins of controlled heat distortion points which comprises reacting acrolein and pentaerythritol in the presence of an acid catalyst whereinfrom 1.3 to 1.9 moles of acrolein are reacted per mole of pentaerythritol to form a liquid. condensate, stripping off volatiles which are distillable from said condensate at temperatures of 71 C. to C. and 3 mm. to 7.5 mm. of pressure to form a'liquid resin, adding monomeric isolated 3,9 divinylspirobi(m-dioxane) to the liquid resin in an amountof 2% to 25% of the total composition to form a curable composition, and curing said composition to a synthetic resin by heating in the presence of an acid catalyst.

References Cited in the file of this patent UNITED STATES PATENTS 2,401,776 Rothrock June 11, 1946 2,687,407 Orth Aug. 24, 1954 FOREIGN PATENTS 868,351 Germany Feb. 23, 1953 870,032 Germany Mar. 9, 1953 OTHER REFERENCESI Schulz et aL: Angewandte Chemie, vol. 62, No. 5, pp. 105,113, 114, 117, 118. Copy in Scientific Library. 

1. PROCESS OF MAKING A CURABLE COMPOSITION WHICH COMPRISES REACTING ACROLEIN AND PENTAERYTHRITOL IN THE PRESENCE OF AN ACID CATALYST WHEREIN FROM 1.3 TO 1.9 MOLES OF ACROLEIN ARE REACTED PER MOLE OF PENTAERYTHRITOL TO FORM A LIQUID CONDENSATE, STRIPPING OFF VOLATILES WHICH ARE DISTILLABLE FROM SAID CONDENSATE AT TEMPERATURES OF 71* C. TO 80*C. AND 3 MM. TO 7.5 MM. OF PRESSURE TO FORM A LIQUID RESIN, AND ADDING MONOMERIC ISOLATED 3,9-DIVINYLSPIROBI(M-DIOXANE) TO THE LIQUID RESIN IN AN AMOUNT OF 2% TO 25% OF THE TOTAL COMPOSITION TO FORM A CURABLE COMPOSITION. 